Optimal decentralized Kalman filter

The Kalman filter is a powerful state estimation algorithm which incorporates noise models, process model and measurements to obtain an accurate estimate of the states of a process. Implementation of conventional Kalman filter algorithm requires a central processor that harvests measurements from all the sensors in the field. Central algorithms have some drawbacks such as reliability, robustness and high computation which result in a need for non-central algorithms. This study takes optimality in decentralized Kalman filter (DKF) as its focus and derives the optimal decentralized Kalman filter (ODKF) algorithm, in case the network topology is provided to every node in the network, by introducing global Kalman equations. ODKF sets a lower bound of estimation error in least squares sense for DKF

The nature of upright and inverted face representations: an adaptation-transfer study of configuration

Published online xxx Keywords: Face inversion effect t r a c t It is considered that whole-face processing of spatial structure may only be possible in upright faces, with only local feature processing in inverted faces. We asked whether this was due to impoverished representations of inverted faces. We performed two experiments. In the first, we divided faces into segments to create 'exploded' faces with disrupted second-order structures, and 'scrambled' faces with altered first-order relations; in the second we shifted features within intact facial outlines to create equivalent disruptions of spatial structure. In both we assessed the transfer of adaptation between faces with altered structure and intact faces. Scrambled adaptors did not adapt upright or inverted intact faces, indicating that a whole-face configuration is required at either orientation. Both upright and inverted faces showed a similar decline in aftereffect magnitude when adapting faces had altered second-order structure, implying that this structure is present in both upright and inverted face representations. We conclude that inverted faces are not represented simply as a collection of features, but have a whole-face configuration with second-order structure, similar to upright faces. Thus the qualitative impairments induced by inversion are not due to degraded inverted facial representations, but may reflect limitations in perceptual mechanisms. ª 2011 Elsevier Srl. All rights reserved. Faces are processed by the human visual system in a manner that is sufficiently precise and efficient to allow us to rapidly identify thousands of individual faces, some at a single glance. This expert processing is orientation-dependent, in that recognition of faces is far better when faces are viewed in the customary upright orientation than when seen inverted, i.e., rotated in the picture plan

A plasmonic enhanced photodetector based on silicon nanocrystals obtained through laser ablation

We present a proof-of-concept photodetector which is sensitive in the visible spectrum. Silicon nanocrystals (Si-NCs) obtained by laser ablation are used as the active absorption region. Si-NC films are formed from a polymeric dispersion. The films are sandwiched between thin insulating films to reduce the electrical leakage current. Furthermore, Ag nanoparticles are integrated with the photodetector to enhance the visible response using plasmonic effects. The measured photocurrent is resonantly enhanced, which is explained in terms of enhanced local fields caused by localized plasmons. The UV-vis spectrum of Ag nanoparticles is also measured to verify the resonance. © 2012 IOP Publishing Ltd

Quadratic time algorithm for inversion of binary permutation polynomials

International audienceIn this paper, we propose a new version of the Lagrangian interpolation applied to binary permutation polynomials and, more generally , permutation polynomials over prime power modular rings. We discuss its application to obfuscation and reverse engineering.Quadratic time algorithm for inversion of binary permutation polynomial

Pléiades project: Assessment of georeferencing accuracy, image quality, pansharpening performence and DSM/DTM quality

Pléiades 1A and 1B are twin optical satellites of Optical and Radar Federated Earth Observation (ORFEO) program jointly running by France and Italy. They are the first satellites of Europe with sub-meter resolution. Airbus DS (formerly Astrium Geo) runs a MyGIC (formerly Pléiades Users Group) program to validate Pléiades images worldwide for various application purposes. The authors conduct three projects, one is within this program, the second is supported by BEU Scientific Research Project Program, and the third is supported by TÜBİTAK. Assessment of georeferencing accuracy, image quality, pansharpening performance and Digital Surface Model/Digital Terrain Model (DSM/DTM) quality subjects are investigated in these projects. For these purposes, triplet panchromatic (50 cm Ground Sampling Distance (GSD)) and VNIR (2 m GSD) Pléiades 1A images were investigated over Zonguldak test site (Turkey) which is urbanised, mountainous and covered by dense forest. The georeferencing accuracy was estimated with a standard deviation in X and Y (SX, SY) in the range of 0.45m by bias corrected Rational Polynomial Coefficient (RPC) orientation, using ~170 Ground Control Points (GCPs). 3D standard deviation of ±0.44m in X, ±0.51m in Y, and ±1.82m in Z directions have been reached in spite of the very narrow angle of convergence by bias corrected RPC orientation. The image quality was also investigated with respect to effective resolution, Signal to Noise Ratio (SNR) and blur coefficient. The effective resolution was estimated with factor slightly below 1.0, meaning that the image quality corresponds to the nominal resolution of 50cm. The blur coefficients were achieved between 0.39-0.46 for triplet panchromatic images, indicating a satisfying image quality. SNR is in the range of other comparable space borne images which may be caused by de-noising of Pléiades images. The pansharpened images were generated by various methods, and are validated by most common statistical metrics and also visual interpretation. The generated DSM and DTM were achieved with ±1.6m standard deviation in Z (SZ) in relation to a reference DTM.Airbus Defence and SpaceBEU/2014-47912266-01TÜBİTAK/114Y38

Continuous Evolution of Statistical Estimators for Optimal Decision-Making

In many everyday situations, humans must make precise decisions in the presence of uncertain sensory information. For example, when asked to combine information from multiple sources we often assign greater weight to the more reliable information. It has been proposed that statistical-optimality often observed in human perception and decision-making requires that humans have access to the uncertainty of both their senses and their decisions. However, the mechanisms underlying the processes of uncertainty estimation remain largely unexplored. In this paper we introduce a novel visual tracking experiment that requires subjects to continuously report their evolving perception of the mean and uncertainty of noisy visual cues over time. We show that subjects accumulate sensory information over the course of a trial to form a continuous estimate of the mean, hindered only by natural kinematic constraints (sensorimotor latency etc.). Furthermore, subjects have access to a measure of their continuous objective uncertainty, rapidly acquired from sensory information available within a trial, but limited by natural kinematic constraints and a conservative margin for error. Our results provide the first direct evidence of the continuous mean and uncertainty estimation mechanisms in humans that may underlie optimal decision making

The Mere Exposure Effect in the Domain of Haptics

Background: Zajonc showed that the attitude towards stimuli that one had been previously exposed to is more positive than towards novel stimuli. This mere exposure effect (MEE) has been tested extensively using various visual stimuli. Research on the MEE is sparse, however, for other sensory modalities. Methodology/Principal Findings: We used objects of two material categories (stone and wood) and two complexity levels (simple and complex) to test the influence of exposure frequency (F0 = novel stimuli, F2 = stimuli exposed twice, F10 = stimuli exposed ten times) under two sensory modalities (haptics only and haptics & vision). Effects of exposure frequency were found for high complex stimuli with significantly increasing liking from F0 to F2 and F10, but only for the stone category. Analysis of ‘‘Need for Touch’ ’ data showed the MEE in participants with high need for touch, which suggests different sensitivity or saturation levels of MEE. Conclusions/Significance: This different sensitivity or saturation levels might also reflect the effects of expertise on the haptic evaluation of objects. It seems that haptic and cross-modal MEEs are influenced by factors similar to those in the visual domain indicating a common cognitive basis